It was suggested in another thread that "lake classification" should be explained.

I think that's an idea with merit, so I decided to kick off such a thread.

The lion's share of dissension within our forum is due to geographical differences.

While a question may be posed by an angler who fishes a mesotrophic impoundment,

he's going to receive many replies from anglers who fish eutrophic natural lakes, and vice versa.

Like anything else, once understand, it's a piece of cake:

By far, the most important lake classification is whether you're dealing with a Natural lake or Artificial lake.

Beyond that, you can build it out to nine trophic states if you so desire. The three major trophic states are as follows:

> Oligotrophic = Young (usually glacial)

> Mesotrophic = Mid-aged (said of natural and artificial waters)

> Eutrophic = Old (may be glacial, seabed, sinkhole, et al)

We arrive at a total nine by subdividing each of the three major trophic states into three stages:

> Early-Stage (oligo, meso & eutro)

> Mid-Stage (oligo, meso & eutro)

> Late-Stage (oligo, meso & eutro)

By the way, "late-stage eutrophic" lakes are comically referred to as Early Cornfield.

If I forgot to mention that, I'll bet Muddy would've filled you in ;D

Because eutrophic lakes are old, they're characterized by advanced sedimentation, lowered water clarity and high fertility

(greatest fish-pounds per acre). If you're fishing a eutrophic natural lake, weeds are the key, as bass will live-and-die

between the shoreline and the outer weed-line. The overwhelming majority of natural lakes in the United States are eutrophic.

When living in New Jersey we were surrounded by eutrophic natural lakes such as Paulinskill,

Carnegie Lake and Lake Muscenetcong to name a few.

The eutrophic zone of natural lakes begins at the bottom of Florida and runs northward to New Jersey.

The northern border of eutrophic natural waters runs westward past the bottom of Lake Michigan to the Canadian border in Montana.

They are however, conspicuously absent west of the Rocky Mountains.

Artificial impoundments typically lack lush vegetation, either due to marginal bottom content or pool level fluctuations.

Therefore, bass holding features in a manmade lake have no depth bounds, where bass depth is limited only by the oxycline.

If your lake is a mesotrophic impoundment, pay particular attention to what Catt posts.

Oligotrophic natural lakes are typically deep, clear and infertile waters (low biomass per acre).

Unless you're fishing in Canada, it's not likely that you'll encounter many oligotrophic natural lakes.

On the othe hand, "artificial" oligotrophic lakes are a whole other animal. Since artificial oligo lakes are manmade, their population is growing.

In contrast, the population of natural lakes tends to shrink (early cornfield).

Roger

This thread has been a long time coming!

Don't older lakes get clearer water? Might not have understood?

This thread has been a long time coming!

Don't older lakes get clearer water? Might not have understood?

Chris, the aging process of a lake is a combination of erosion, sedimentation, increasing algae,

increasing fertility, diminishing depth and diminishing water clarity. Although that may sound bad,

it is very good to a point, and furthermore depends on the species of fish in question (e.g. lake trout or catfish?).

When we see a picture-perfect postcard of a pristine Canadian lake, we're looking at a young lake

where the glacier was last to recede. The lake in the picture is crystal-clear with bold shield rock shores,

peppered with white birch trees. A gorgeous portrait, Yes!a fertile lake, No!

What's not so visible is that those clear, cool, deep waters are infertile, and in some cases borderline sterile.

Oligotrophic ecosystems are fragile and easily skimmed by intelligent angling, but such is not the case with eutrophic waters.

As a lake ages, rock is ultimately turned to sand, sedimentation gradually fills in the basin thereby reducing the depth.

As the area of soft sedimentary bottom increases, the more sediment there is in suspension, which progressively degrades water clarity.

Let's take a look at your own Kentucky Lake.

Several years ago, Rick Clunn weighed in two smallmouth bass at a Kentucky Lake tourney.

Both smallmouth bass weighed exactly 5 lbs, 10 oz! I seriously doubt that he or anyone else might repeat that feat today.

Why would I say such a thing? In a word eutrophication. As Kentucky Lake ages, it becomes progressively more suited to largemouth bass

and progressively less suited to smallmouth bass. The Department of Natural Resources will fight it, but as always, Big Mama will win.

Roger

Natural lakes are generally classified as the opening post describes, however man made impoundments or reservoirs also fall into classifications based on the terrain they are located in and the type of dams they have.

In-Fishermen was the first publication to make this distinction and is also a good source of information on oligotrophic, mesotrophic and eutrophic natural lakes, as they relate to fishing.

Man made dams are placed at locations that will hold back water from seasonal run off or year around river flows. The dams that are used for power generation are placed in narrow area of river valley or mountain canyon. Flood control dams are similar, except usually associated with flood control or water storage. The difference is important to know as power generating dams create current.

Out west we have four types of impoundments and dams;

Canyon reservoir; deep steep rock walled river; Colorado river system, lakes Power, Mead, Mojave & Havasu are examples.

Highland power generation reservoir; Lake Shasta and most of the larger motherlaod river dams.

Highland water storage; Lake Casitas, Castaic and most of the SoCal reservoirs.

Hill land; Lake Berryessa is a good example.

Natural mesotrophic lake; Clear Lake for example.

Natural oligotropic lakes out west have too cold of water to support bass; Lake Tahoe is the largest of the natural lakes located in the high Sierra range, however hundreds of high elevation natural lakes.

The other lake classifications are;

Flat land; reservoirs located in the plains states.

Low land; reservoirs located near coastal plains.

All natural lakes age and eventually become a meadow as they fill in with run off soil or silt, with the possible exception of Canadian shield lakes and high elevation lakes. Reservoirs also age, however start out very fertile due to the newly flooded land and without dragging may in time fill in with silt from run off.

WRB

I've read a book by infisherman covering the different classications.

Since the lake is filled in ultimately through sedimentation, the upper ends of the lake should fill in first creating two different situations on different parts of the lake. Right?

Also by looking at a map, how would we me able to tell which stage the lake in that area is in?

Mottfia

I've read a book by infisherman covering the different classications.

Since the lake is filled in ultimately through sedimentation, the upper ends of the lake should fill in first creating two different situations on different parts of the lake. Right?

Speaking of artificial reservoirs, correct.  Of course that also depends on what's further upstream on the upper end of a lake.  If by going way upstream you wind up running into another dam, that dam and lake behind it becomes a catch basin which prevents excessive amounts of sediment from entering the upper reaches of the lower lake.  

Case in Point:  Lake of the Ozarks in mid Missouri is a hill land lake built in 1931.  50,000 surface acres.  Up until the mid 80's the lake was normally very off colored and dirty due to the amount of sediment that flushed into the lake from the head waters of the osage river which drained a lot of farm land.  Along comes Truman dam and Truman lake in the early 80's and suddenly LOZ starts clearing up.  Truman was now catching a lot of that sediment and preventing it from entering LOZ.  

LOZ still get dirty to muddy from time to time when they dump water from Truman when it gets high or they're generating power and LOZ's water has something of a "tang" to it now due to over building of the shorelines with housing, many of which are on septic systems.  Overall though it's still cleaner than it once was.

Also by looking at a map, how would we me able to tell which stage the lake in that area is in?

Mottfia

Without knowing the actual bottom contour over time, it's difficult to tell.  I have a couple maps of Illinois lakes that were contoured in the early 70's.  These lakes also have farmland draining into their headwaters.  Driving around on the lake with the depthfinder on it's clear these lakes have filled in.  The upper ends of the lake begin to flatten out and lose depth.  One of these lakes has lost at least 5-6' of depth down by the dam due to siltation.  Normally though, if you're on a lake and observe shorelines that drop fairly quickly into the water but yet, the graph depth readings tend to show that dropping less so underwater you've probably got a situation where siltation has filled in the bottom.  One lake in Missouri I fish, 220 acres, had an upper end that was all cut up by little creek channels and ditches along with standing timber.  The timber long ago fell over and the entire upper end, which used to be a great place to fish, is now one big 3' deep mud flat.

Google earth can be useful though depending on the satellite shots of the lake and when they were taken.  Often you can see creeks or rivers feeding dirty water into lakes or see light, muddy bottoms on the upper ends of the lake.  

Since the lake is filled in ultimately through sedimentation, the upper ends of the lake should fill in first creating two different situations on different parts of the lake. Right?

Mottfia

The impounding dam is typically situated at the tail of the lake's basin. As a result, the upper-end or headwaters is typically a riverine environment whose sediment will ultimately end up in the lake basin near the dam (tailwaters).

Perhaps more importantly, the rate of erosion and sedimentation will depend on the resident substrate.

For this same reason, the eutrophication rate in each creek arm can vary broadly based on the substrate thereat,

whether it's predominantly rock, sand, clay, mire, etc, and its relative location with regard to water exchange rate.

Also by looking at a map, how would we me able to tell which stage the lake in that area is in?

There are two approaches to evaluating trophic status, one is scientific and the other if for you and I.

The scientific approach uses a complex formula to determine the Carlson's Index, by factoring in three variables

> Water Transparency (secchi disk readings)

> Chlorophyll Level       (suspended algae)

> Total Phosphorus      

The results are then calculated to determine the Carlson Value (below):

Carlson's Index

20 to 35 = Oligotrophic

35 to 55 = Mesotrophic

55 to 70 = Eutrophic

Over 70 = Hypereutrophic

Obviously, you and I are not going to be bothered with any Carlson Index. Furthermore, it's a very poor tool in the field.

Most large lakes simultaneously possess different trophic states within the same waterbody. For example,

most mesotrophic lakes have one or more eutrophic bays. For the fisherman, lake classificiation is not an exact science,

nevertheless, we must be able to distinguish between Natural and Artificial, and between Young and Old:

Again, if the waterbody is old, it will be shallower, dingier and weedier than its meso and oligo counterparts.

If you break out the electronics, it will also be warmer and contain less dissolved oxygen.

The dissolved oxygen in a late-stage eutrophic lake (early-stage cornfield) ultimately flirts with zero,

when the population of bullheads and carp finally cash out.

The lake is now dead, which will ultimately dry up and generate lush drifts of dog fennel ;-)

Roger

I just read threw my in fisherman book and it says that bass prefer the early euthropic lakes over the other lake types. So if the lake contains properties of multiple types, lets say early euthropic and mesothropic then the majority of large mouth should relate to the eurthropic area, right?

Mottfia

I just read threw my in fisherman book and it says that bass prefer the early euthropic lakes over the other lake types. So if the lake contains properties of multiple types, lets say early euthropic and mesothropic then the majority of large mouth should relate to the eurthropic area, right?

Mottfia

Absolutely!

But the meso areas will hold more smallmouth and walleyes.

Few large reservoirs will have early eutrophic zones located where the majority of bass prefer; main lake outside structure. The euthrophic areas are generally located in the back of bays or creek arms and make excellent spawning and nursery areas for the young fish; they can hide in the weeds.

In a natural lake (or pond) the main lake bottom collects the soil sediments and decayed matter that robs the water of DO levels high enough for bass, plus the warming water stratifies into layers that further reduce DO levels. Bass need between 3 to 12 mg/l to survive and the green aquatic weed growth helps to regenerate DO along with wind wave action. This one reason that bass prefer weed edge break lines in natural lakes or shallow reservoirs.

Since bass can't read, they simple go where the conditions best suited for them; comfortable water temperature, good DO levels, food and shelter, regardless of the lakes classification.

The only natural bass lake out west where I fish is Clear Lake, a  early eutrophic lake. The delta area is a complex system of rivers and sloughs that could be early euthrophic. All the reservoirs are mesotrophic, with the exception of the Imperial area on the lower Colorado river which is eutrophic shallow expanse of reeds and channels. They all have excellent bass fishing.

WRB

Few large reservoirs will have early eutrophic zones located where the majority of bass prefer; main lake outside structure. The euthrophic areas are generally located in the back of bays or creek arms and make excellent spawning and nursery areas for the young fish; they can hide in the weeds.

In a natural lake (or pond) the main lake bottom collects the soil sediments and decayed matter that robs the water of DO levels high enough for bass, plus the warming water stratifies into layers that further reduce DO levels. Bass need between 3 to 12 mg/l to survive and the green aquatic weed growth helps to regenerate DO along with wind wave action. This one reason that bass prefer weed edge break lines in natural lakes or shallow reservoirs.

Since bass can't read, they simple go where the conditions best suited for them; comfortable water temperature, good DO levels, food and shelter, regardless of the lakes classification.The only natural bass lake out west where I fish is Clear Lake, a early eutrophic lake. The delta area is a complex system of rivers and sloughs that could be early euthrophic. All the reservoirs are mesotrophic, with the exception of the Imperial area on the lower Colorado river which is eutrophic shallow expanse of reeds and channels. They all have excellent bass fishing.

WRB

"C'est fini!  

Natural lakes aside, this segment discusses the terrestrial classifications of Artificial Lakes.

(Incidentally, artificial lake is synonymous to reservoir' and impoundment'.)

By using the shotgun approach, this post attempts to involve everyone in the United States,

without any regional bias. As noted below, there are six basic terrestrial classes of artificial lakes:

Reservoir Class       Mean Clarity       Impoundment       Weight Plateau

> Lowland       Murky to Clear       Concrete       18 lb

> Flatland       Mostly Dingy       Earthen (concrete spillways)      15 lb

> Hill-Land       Clear but Stained Earthen (concrete spillways)      9 lb

> Highland       Mostly Clear       Earthen OR Concrete       12 lb

> Plateau       Clear to Stained      Earthen (concrete spillways) 6 lb

> Canyon       Crystal-Clear       Concrete       9 lb

A weight plateau is simply a sticking point where many bass of similar weight tend to crop up, the most pervasive being 9 pounds.

Plateaus are normally the product of forage base, year-class success, gender and age constraints.

Weight plateaus are remarkably repetitive, and are readily disclosed using historic records such as state citation programs,

biggest fish per tournament, electroshocking, annual contests sponsored by beer and magazine companies, etc.

Roger

Roger, can you give me a layman's definition of the Weight Plateau. I don't understand it.

Mottfia

Roger, can you give me a layman's definition of the Weight Plateau. I don't understand it.

Mottfia

Okay, you have a sample of 50,000 boated bass, their length, girth & weight.

You can analyze that sample in three different manners: Average - Mode - Median.

Without complicating the explanation, "weight plateau" refers to the mode.

In other words, weight points where the weights bunch up (sticking points).

Once you surpass a plateau (like a stock resistance level), the weight is likely to spurt.

You may spend 10 years of your life reaching the 9-lb plateau, then the very next bass

you boat over 9 lbs may weigh 11lb, 3oz, because the next weight plateau in most waterbodies is 12 pounds.

To use buck bass as an example, the weight plateau of male bass is 4 lbs, while the ceiling weight is 6 lbs.

This is purely statistical of course, and exceptions are rampant. Hope that helps.

Roger

Thanks Roger; Copied and filed. Greenwood lake had a few different types of water going on, that's where I first noticed it. Those 2 arms by Long Pond and the old 17 bridge , were definitely Eutrophic and held some nice LMB.

Few large reservoirs will have early eutrophic zones located where the majority of bass prefer; main lake outside structure. The euthrophic areas are generally located in the back of bays or creek arms and make excellent spawning and nursery areas for the young fish; they can hide in the weeds.

In a natural lake (or pond) the main lake bottom collects the soil sediments and decayed matter that robs the water of DO levels high enough for bass, plus the warming water stratifies into layers that further reduce DO levels. Bass need between 3 to 12 mg/l to survive and the green aquatic weed growth helps to regenerate DO along with wind wave action. This one reason that bass prefer weed edge break lines in natural lakes or shallow reservoirs.

Since bass can't read, they simple go where the conditions best suited for them; comfortable water temperature, good DO levels, food and shelter, regardless of the lakes classification.

The only natural bass lake out west where I fish is Clear Lake, a early eutrophic lake. The delta area is a complex system of rivers and sloughs that could be early euthrophic. All the reservoirs are mesotrophic, with the exception of the Imperial area on the lower Colorado river which is eutrophic shallow expanse of reeds and channels. They all have excellent bass fishing.

WRB

 Not all the time, ask anyone fishing natural lakes on the North East Coast, the weedy flats, all through them and particularly if there is cover like a big rock in the middle are great bass magnets. If you were to only fish the weed lines and not the flats themselves you would miss out on some of the best fishing on these lakes.

Roger, can you give me a layman's definition of the Weight Plateau. I don't understand it.

Mottfia

Okay, you have a sample of 50,000 boated bass, their length, girth & weight.

You can analyze that sample in three different manners: Average - Mode - Median.

Without complicating the explanation, "weight plateau" refers to the mode.

In other words, weight points where the weights bunch up (sticking points).

Once you surpass a plateau (like a stock resistance level), the weight is likely to spurt.

You may spend 10 years of your life reaching the 9-lb plateau, then the very next bass

you boat over 9 lbs may weigh 11lb, 3oz, because the next weight plateau in most waterbodies is 12 pounds.

To use buck bass as an example, the weight plateau of male bass is 4 lbs, while the ceiling weight is 6 lbs.

This is purely statistical of course, and exceptions are rampant. Hope that helps.

Roger

OK let's see if I have this right. The weight plateau is the maximum size that a typical fish would reach in its lifetime (assuming it survives long enough) under the conditions available within the specific reservoir.

Mottfia

OK let's see if I have this right. The weight plateau is the maximum size that a typical fish would reach in its lifetime

Actually, maximum weight and weight plateau is not the same thing.

Let me use a tall mountain as an analogy. The upslope of the mountain represents the weight gain of a bass.

At birth the weight of the bass is represented by the base of the mountain. As the bass matures,

its weight climbs up the mountain slope toward the crest. The crest of the mountain designates the maximum weight of the bass,

but has nothing to do with the weight plateaus along the way. A weight plateau is analogous to a flat stairstep encountered

as you ascend a mountain. The first flat bench we encounter nearest to the base of the mountain represents the first plateau.

With respect to bass weight, let's label the first plateau "3 pounds" (that actually IS the first plateau).

This glass ceiling is the byproduct of growth rate, mortality rate, gender and age constraints.

When the weight of a bass exceeds the first plateau (3 lbs), it tends to vary more randomly until flattening out again at the second plateau,

for instance 6 pounds. There are several plateaus along the way before a bass reaches maximum weight (the mountain crest).

Most weight plateau have a political handle, that is to say: Trophy-class, Record-class, World-class and Freak-class.

If 'weight plateau' is still unclear to you, feel free to shoot me a PM and we'll knock it down.

Roger

Plateau weights from the In-Fishermen articles are based historical data on Gaussian bell curves, however didn't take into consideration Florida largemouth bass being transplanted into high-land or hill-land reservoirs.

There hasn't been any valid numbers of 18 lb bass from low-land reservoirs. 15 lbs would be a better plateau figure for reservoirs the have a FLMB population.

WRB